Cigarette filters disintegrate relatively slowly and therefore are an annoyance to broad sections of the population in places where there is much smoking.
For most cigarette filters, cellulose acetate fibers are being used today having an acetyl number between 53 and 57% (cf. for example U.S. Pat. No. 2,953,837. The numerical values cited in this patent, namely 38% to 41% for the acetyl content, correspond to the aforesaid values of 53 to 57% for the acetyl number).
Compared with other polymers, in particular synthetic ones, such a cellulose acetate is indeed biodegradable, but the time spans after which cigarette filters of such fibers have disappeared at least optically under the action of environmental influences are too long in today's estimation.
Similarly to the cigarette filters, this applies also to other structures of cellulose acetate, such as films, foils, sheets or other objects of cellulose acetate obtained for example by injection molding, extruding or blow-molding: when such structures are stored for example in dumps, it takes too long until these structures are completely biodegraded.
Filter tows and tobacco smoke filter elements of cellulose acetate fibers, on the surface of which an additive is provided, are known for example from German Patent 1079521. According to this German Patent 1079521, the additive applied on the surface of the cellulose acetate fibers serves to improve the roughness of these fibers. However, no suggestion can be found in German Patent 1079521 for the acceleration of the biodegradability of the filter tows and of the tobacco smoke filter elements.
Further, U.S. Pat. No. 5,141,006 describes filter tows and tobacco smoke filter elements of cellulose acetate fibers in which an additive is present. According to U.S. Pat. No. 5,141,006, with the additive in the cellulose acetate fibers in particular the filter efficiency for nicotine is to be improved. However, also U.S. Pat. No. 5,141,006 gives no indication of the possibility to accelerate the biodegradability of the filter tow and of the tobacco smoke filter elements.
German patent application 40 13 293 and German patent application 40 13 304 do indeed describe cigarette filters which under the action of environmental influences decompose relatively fast, but these cigarette filters consist of a section of transverse-axially compacted fiber skeins of fibers of spun PHB (polyhydroxybutyric acid) or a copolymer of PHB and PHV (polyhydroxyvalerc acid). These polymers, however, are not at present being used for the manufacture of filter tow and tobacco smoke filter elements, at least not to any appreciable extent, which may be due to
the insufficient industrial availability of the polymers. PA1 the effect on the taste of the smoke different from cellulose acetate and PA1 as yet unclarified process technological problems in the processing of such polymers to filter tows and tobacco smoke filter elements (for example in connection with the hardening of such tobacco smoke filter elements or in connection with the use of problematic solvents in spinning threads from these polymers). PA1 the required quantity of said additives is very high, and this, by the way, considerably limits the possibilities of use of such plastic materials, and PA1 due to their high price, the mentioned additives greatly increase the cost of the objects made from the described plastic materials. An additional factor is that for some of the additives described in German disclosure 39 14 022, approval under food legislation or approval under TVO (Tobacco Ordinance) is not possible or hardly possible, both because of the required quantities and because of their toxicity, thus making impossible the use of the plastic materials described in German disclosure 30 14 022 for e.g. filter tows and tobacco smoke filter elements, such as cigarette filters. In addition, no hint to the possibility of accelerating the biodegradation of filter tows and tobacco smoke filter elements can be found in German patent application 39 14 022; nor would the formulation described in German disclosure 39 14 022 be suitable for the manufacture of filter tows and tobacco smoke filter elements because of the overly high proportion of plasticizer in the cellulose acetate. PA1 for mass-produced articles of cellulose acetate there is still a need to make them better biodegradable and PA1 also for structures from cellulose acetate which are governed by the food law and/or the tobacco ordinance, such as filter tows consisting of cellulose acetate fiber material, as well as tobacco smoke filter elements made from such a filter tow, no solution to accelerate their biodegradation is known as yet. PA1 the cellulose acetate plasticizer be biodegradable and/or that it accelerate the microbiological growth on the cellulose acetate filaments and staple fibers or PA1 that the adhesive be water-soluble and/or biodegradable, it being most preferred that the adhesive be a starch glue or a polyvinyl acetate glue. PA1 Spinning cellulose acetate filaments by extruding a solution of cellulose acetate in acetone through a multi-hole spinneret and if necessary subsequently cutting of the cellulose acetate filaments to cellulose acetate staple fibers and PA1 gathering a plurality of the cellulose acetate filaments and/or staple fibers thus obtained to a filter tow. PA1 be applied during the manufacture of the filter tow, but after the formation of the cellulose acetate filaments, onto these filaments or onto the cellulose acetate staple fibers formed therefrom (for example, the additive can be applied on the filaments immediately before the cutting of the cellulose acetate filaments into cellulose acetate staple fibers, or the additive can be applied on the finished filter tow, that is, after the gathering of the cellulose acetate filaments and/or staple fibers to a filter tow, on the filaments and/or staple fibers or PA1 be applied during the manufacture of the tobacco smoke filter element, but prior to the transverse-axial compacting of the filter tow, onto the cellulose acetate filaments and/or staple fibers (preferably the additive is applied on the cellulose acetate filaments and/or staple fibers immediately after the filter tow has been provided with a plasticizer or adhesive).
Finally from German patent application 39 14 022 new plastic materials are known which are easily biodegradable by composting and their use for the manufacture of sheaths/containers for oil lamps, eternal light oil candles, composition oil lamps, other grave lamp models, sacrificial lamps and foils is known. As plastic materials there is cited in German patent application 39 14 022 a plastic material on the basis of e.g. cellulose acetate with additives such as citric acid esters, polyester, phosphoric acid esters and organic iron compounds. As organic iron compounds there may be used for example ferrocenes, i.e. derivatives of bis-(cyclopentadienyl)-iron or iron (II) acetylacetonate.
However, the plastic materials described in German patent application 39 14 022 are hardly suitable or unsuitable for the manufacture of mass-produced articles, because
A summary of the prior art shows, therefore, that